Longitudinal Positioning Tool for a Rod String

ABSTRACT

A positioning tool longitudinally positions a rod string relative to a tubing string while the rod string remains by a drive head. An upper hollow shaft member of the tool is fixed to the rod string by a rod clamp while a lower hollow shaft member is slidably coupled to the upper hollow shaft member such that the upper and lower hollow shaft members are rotatable together and longitudinally adjustable relative to one another. The bottom end of the lower hollow shaft member is arranged to be coupled to the rotatable output of the drive head. A hydraulic lifting assembly is coupled between the upper and lower shaft members to hydraulically control the longitudinal position of the rod string and upper shaft member relative to the tubing string and the lower shaft member.

This application claims the benefit under 35 U.S.C.119(e) of U.S. provisional application Ser. No. 61/602,379, filed Feb. 23, 2012.

FIELD OF THE INVENTION

The present invention relates to a tool arranged to support a rod string at different longitudinal positions relative to a tubing string while permitting the rod string to remain connected to a drive head so as to be rotatable relative to the tubing string at each of the different longitudinal positions.

BACKGROUND

Various types of downhole equipment (for example downhole pumps) at the bottom end of a tubing string are driven to rotate by rod string extending longitudinally through the tubing string. A bottom end of the rod string is coupled to the downhole equipment while a top end of the rod string is coupled to the rotary output of a drive head supported above the tubing string. The rod string is typically formed of a plurality of rods connected in series with one another. As the rod is rotated, each connection between adjacent rods in the rod string typically comes into contact with an inner surface of the tubing string at a consistent elevation which may wear through the tubing string.

SUMMARY OF THE INVENTION

According to one aspect of the invention there is provided a positioning tool for longitudinally positioning a rod string supported to rotate within a tubing string by a drive head with a rotatable output supported above the tubing string, the tool comprising:

a rod clamp arranged to be clamped about the rod string at a location spaced above the drive head;

an upper hollow shaft member arranged to be fixed to the rod clamp so as to be arranged to receive the rod string therethrough and be arranged to rotate with the rod string;

a lower hollow shaft member slidably coupled to the upper hollow shaft member such that the upper and lower hollow shaft members are rotatable together with one another and are longitudinally adjustable relative to one another, the lower hollow shaft member having a bottom end arranged to be coupled to the rotatable output of the drive head;

a hydraulic lifting assembly comprising:

-   -   a lower portion arranged to be supported above the tubing         string;     -   an upper portion arranged to support the upper hollow shaft         member and rod clamp thereon;     -   the upper portion being coupled to the lower portion so as to be         longitudinally movable relative to the lower portion between a         retracted position in which the rod clamp is supported thereon         at a first elevation relative to the tubing string and an         extended position in which the upper portion is raised upwardly         relative to the retracted position and the rod clamp is         supported thereon at a second elevation relative to the tubing         string which is greater than the first elevation; and     -   a hydraulic actuator arranged to operate the upper portion         between the retracted position and the extended position; and

at least one bearing member supporting the upper hollow shaft member for rotation relative to the tubing string.

The longitudinal positioning tool permits the longitudinal position of the rod string to be adjusted without affecting the normal operation of the drive head used to rotate the rod string. In this instance, the elevation of each connection between adjacent rod sections in the rod string can be adjusted periodically or continuously stroked so that the potential wear of the rod connections on the inner surface of the tubing string can be distributed over a larger area along the tubing string. The life of the tubing string before the rotating rod string wears through the tubing string can thus be considerably extended. The tool can be fitted to any industry drive for rotating the rod, or alternatively, the tool can be integrally cast with the drive as one complete rod driving and positioning tool capable of left or right rotation while stroking up and down at the same time.

Preferably the upper and lower portions of the hydraulic lifting assembly comprise tubular casings which are telescopically connected. More particularly, one of the upper portion and the lower portion may comprise a hydraulic chamber and the other one of the upper portion and the lower portion may comprise a piston received within the hydraulic chamber. In this instance the hydraulic actuator is coupled to the hydraulic chamber so as to be arranged to control a volume of hydraulic fluid in the hydraulic chamber for operating the upper portion between the retracted position and the extended position.

Preferably the lower portion of the hydraulic lifting assembly is arranged to be supported on the drive head.

In a preferred embodiment a bearing assembly supports the upper hollow shaft member rotatably on the upper portion of the hydraulic lifting assembly and the lower portion of the hydraulic lifting assembly is arranged to be supported on the drive head in fixed relation to the tubing string.

An additional bearing assembly may be supported between the lower portion of the hydraulic lifting assembly and the lower hollow shaft member such that the lower hollow shaft member is rotatably and radially supported relative to the lower portion of the hydraulic lifting assembly.

Preferably a spline connection slidably couples the upper hollow shaft member to the lower hollow shaft member.

According to a second aspect of the present invention there is provided a rod driving tool for longitudinally positioning and driving rotation of a rod string relative to a tubing string receiving the rod string therein, the tool comprising:

a drive head including housing supported above the tubing string and a rotatable output arranged to receive the rod string concentrically therethrough;

a rod clamp arranged to be clamped about the rod string at a location spaced above the drive head;

an upper hollow shaft member arranged to be fixed to the rod clamp so as to be arranged to receive the rod string therethrough and be arranged rotate with the rod string;

a lower hollow shaft member slidably coupled to the upper hollow shaft member such that the upper and lower hollow shaft members are rotatable together with one another and are longitudinally adjustable relative to one another;

the lower hollow shaft member being coupled to the rotatable output of the drive head for rotation therewith relative to the housing of the drive head;

a hydraulic lifting assembly comprising:

-   -   a lower portion supported on the housing of the drive head;     -   an upper portion supporting the upper hollow shaft member and         rod clamp thereon;     -   the upper portion being coupled to the lower portion so as to be         longitudinally movable relative to the lower portion between a         retracted position in which the rod clamp is supported thereon         at a first elevation relative to the tubing string and an         extended position in which the upper portion is raised upwardly         relative to the retracted position and the rod clamp is         supported thereon at a second elevation relative to the tubing         string which is greater than the first elevation; and     -   a hydraulic actuator arranged to operate the upper portion         between the retracted position and the extended position; and

at least one bearing member supporting the upper hollow, shaft member for rotation relative to the housing of the drive head.

One embodiment of the invention will now be described in conjunction with the accompanying drawings in which:

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a front elevational view of a vertical cross section of the tool supported on a drive head above a tubing string.

FIG. 2 is a perspective view of the cross section of the tool according to FIG. 1.

In the drawings like characters of reference indicate corresponding parts in the different figures.

DETAILED DESCRIPTION

Referring to the accompanying figures, there is illustrated a rod positioning tool generally indicated by reference numeral 10. The tool 10 is particularly suited for longitudinally positioning a rod string 12 of the type extending in a longitudinal direction through a tubing string in the field of oil production.

The rod string 12 typically comprises a plurality of rod sections connected in series with one another by respective connections such that the rod string communicates between a drive head 16 adjacent a top end of the string and downhole equipment at the bottom end of the string which is driven to operate by rotation of the rod string. The drive head includes a housing 18 fixed above the tubing string and a rotary output 20 rotatably supported on the housing. The output 20 is driven to rotate by a motor of the drive head. The output is an annular member receiving the rod string concentrically therethrough.

The tool 10 includes a rod clamp 22 arranged to be clamped in fixed relation onto the rod string at a location spaced above the drive head at the top end of the tool and adjacent to a top end of the rod string.

The tool further includes a lower casing 24 and an upper casing 26 which are telescopically connected and supported between the drive head housing 18 and the rod clamp 22. The upper and lower casings are thus relatively slidable in the longitudinal direction between opposed extended and retracted positions such that the overall height of the tool between the top and bottom ends can be adjusted. Adjusting the height of the tool by telescoping the upper and lower casings relative to one another effectively adjusts the height of the rod clamp 22 supported on the top end of the upper casing relative to the drive head upon which the bottom end of the lower casing is supported. This in turn adjusts the height of the rod string relative to the tubing string.

The height is controlled by a hydraulic lifting assembly. The lifting assembly includes a hydraulic chamber 28 formed within the lower casing 24 to define a lower cylinder portion of the lifting assembly. The upper casing has an upper piston portion 30 of the lifting assembly formed thereon. The piston portion is received within the hydraulic chamber 28 of the lower casing for telescoping movement in the longitudinal direction relative to one another. A hydraulic actuator 32 controls the amount of hydraulic fluid pumped into and released from the hydraulic chamber below the piston portion 30 to control the volume of fluid in the chamber and thus control the raising and lowering of the piston of the upper casing relative to the lower casing.

The bottom end of the tool includes a base plate 34 which is arranged to be fixed relative to the housing of the drive head. The lower casing 24 is a cylindrical annular member supported at the bottom end on the base plate 34 in fixed relation therewith. The lower casing is positioned such that the rod string is concentrically received through the central passage in the lower casing. The lower casing includes an inner wall 36 and an outer wall 38 which are integrally joined together at the bottom end to define the hydraulic chamber 28 as the annular space between the inner and outer walls. The chamber 28 is enclosed at the bottom end but is open through the top end for receiving the piston 30 therein.

The upper casing 26 is also a cylindrical annular member forming the piston 30 at the bottom end thereof. The piston is suitably dimensioned for fitting within the annular hydraulic chamber 28 by having a radial thickness which closely fits within the radial dimension of the chamber. Suitable annular grooves 40 are formed in the inner and outer surfaces of the piston for accommodating annular seals which provide a fluid tight seal between the piston and the inner and outer walls of the hydraulic chamber 28 while permitting relative longitudinal sliding therebetween. A main body portion 42 of the upper casing above the piston portion 30 is reduced in outer diameter relative to the piston portion such that the main body portion is reduced in radial thickness from the piston at the bottom end to the opposing top end of the upper casing. A top wall 44 is mounted at the top end of the upper casing to extend radially inward about the full circumference of the upper casing towards a central aperture receiving the rod string concentrically therethrough.

A cap member is secured onto the top end of the upper casing to retain the piston within the chamber and to prevent debris entering the top end of the chamber above the piston. The cap member includes a collar portion 46 externally threaded onto the top end of the lower casing and a top flange 48 which projects radially inward from the top end of the collar portion 46 to extend radially inward over the top end of the chamber 28 by spanning the radial distance from the outer diameter of the lower casing to the outer diameter of the upper casing above the piston.

A top bearing assembly 50 is mounted above the top wall 44 of the upper casing. The top bearing assembly comprises an angle bearing mounted between frusto conical shaped bearing surfaces tapering downwardly and inwardly about the longitudinal axis of the tool to provide both radial and vertical support to the rod clamp supported thereon which in turn suspends the rod string therefrom due to the clamping of the rod clamp in fixed relation onto the rod string.

A shaft assembly extending concentrically through the upper and lower casings and transmits rotary drive from the rotary output of the drive head to the rod string as the rod is varied in elevation. The shaft assembly includes a lower hollow shaft member 52 and an upper hollow shaft member 54 receiving the rod string concentrically therethrough. The upper and lower hollow shaft members are telescopically connected by a spline connection as described in further detail below.

The lower hollow shaft member 52 is a hollow tubular member having a through passage receiving the rod string concentrically therethrough. A bottom end of the lower hollow shaft member includes a hex nut 56 formed thereon for coupling to the rotary output of the drive head for rotation together relative to the tubing string. An inner diameter of the hollow shaft member 52 is larger than the outer diameter of the rod to define an annular space which telescopically receives the upper hollow shaft member therein. The inner surface of the lower hollow shaft member includes longitudinally extending grooves formed therein at circumferentially spaced positions forming one component of the spline connection.

The upper hollow shaft member 54 is also a hollow member including a through passage receiving the rod string concentrically therethrough. The outer diameter of the upper member 54 is arranged to be slidably received into the inner diameter of the lower member. A plurality of longitudinally extending ribs are formed at circumferentially spaced positions for being longitudinally slidable within respective grooves of the lower hollow shaft member in forming the spline connection.

The top end of the upper hollow shaft member includes an integral top flange 58 extending radially outward to form an annular flange spanning overtop of the top wall 44 of the upper casing such that the top bearing assembly 50 is received between the top flange 58 of the upper hollow shaft member and the top wall 44 of the upper casing. An upper surface of the top flange supports the rod clamp thereon in fixed relation.

A lower bearing assembly 60 is mounted between the lower casing and the lower hollow shaft member adjacent the bottom end of the tool to provide radial support between the lower casing which is fixed relative to the tubing string and the lower hollow shaft member received therethrough which rotates with the output of the drive head and the rod string being driven.

In the illustrated embodiment, the lower casing is vertically supported at the bottom end on the base plate 34 which is in turn supported on the housing of the drive head such that the lower casing is fixed relative to the housing of the drive head and the tubing string above which it is supported. The upper casing is in turn coupled to the lower casing for longitudinal sliding responsive to the hydraulic actuator but in a non-rotating manner relative to the housing of the drive head.

The upper hollow shaft member 54 is suspended concentrically within the upper and lower casing members by the top bearing assembly 50 such that the upper hollow shaft member is readily rotatable relative to the casings and the tubing string upon which it is supported.

The lower hollow shaft member is coupled at the bottom end to drive with the output of the drive head and serves to transmit the rotary drive through the upper hollow shaft member to the rod clamp and rod string. The coupling between the upper and lower hollow shaft members ensures the members rotate together for transmitting the rotating drive therethrough while remaining longitudinally slidable to accommodate varying elevations of the rod string relative to the tubing string.

In the arrangement of the present invention, the drive head can be operated in the normal manner to transmit rotation to the rod string for driving downhole equipment. While the rod string is driven to rotate, the hydraulic actuator is operated to cyclically displace or stroke the upper casing relative to the lower casing between a retracted position in which the rod clamp is supported thereon at a first elevation relative to the tubing string and an extended position in which the upper portion of the casing is raised upwardly relative to the retracted position and the rod clamp is supported thereon at a second elevation which is greater than the first elevation. In this manner, any connections within the rod string which may cause wear on the inner surface of the tubing string are rotated through a larger range in the longitudinal direction to distribute potential wear over a larger area.

In further embodiments, the components of the positioning tool may be integrated with a drive head for rotating the rod string resulting in a single tool for both longitudinally positioning the rod string and driving rotation of the rod string with a single integral unit. In this instance the lower casing may be integrated with the housing of the drive head and the lower hollow shaft member maybe integrated with the rotary output of the drive head.

Since various modifications can be made in my invention as herein above described, and many apparently widely different embodiments of same made within the spirit and scope of the claims without department from such spirit and scope, it is intended that all matter contained in the accompanying specification shall be interpreted as illustrative only and not in a limiting sense. 

1. A positioning tool for longitudinally positioning a rod string supported to rotate within a tubing string by a drive head with a rotatable output supported above the tubing string, the tool comprising: a rod clamp arranged to be clamped about the rod string at a location spaced above the drive head; an upper hollow shaft member arranged to be fixed to the rod clamp so as to be arranged to receive the rod string therethrough and be arranged to rotate with the rod string; a lower hollow shaft member slidably coupled to the upper hollow shaft member such that the upper and lower hollow shaft members are rotatable together with one another and are longitudinally adjustable relative to one another, the lower hollow shaft member having a bottom end arranged to be coupled to the rotatable output of the drive head; a hydraulic lifting assembly comprising: a lower portion arranged to be supported above the tubing string; an upper portion arranged to support the upper hollow shaft member and rod clamp thereon; the upper portion being coupled to the lower portion so as to be longitudinally movable relative to the lower portion between a retracted position in which the rod clamp is supported thereon at a first elevation relative to the tubing string and an extended position in which the upper portion is raised upwardly relative to the retracted position and the rod clamp is supported thereon at a second elevation relative to the tubing string which is greater than the first elevation; and a hydraulic actuator arranged to operate the upper portion between the retracted position and the extended position; and at least one bearing member supporting the upper hollow shaft member for rotation relative to the tubing string.
 2. The tool according to claim 1 wherein the upper and lower portions of the hydraulic lifting assembly comprise tubular casings which are telescopically connected.
 3. The tool according to claim 1 wherein one of the upper portion and the lower portion comprises a hydraulic chamber and the other one of the upper portion and the lower portion comprises a piston received within the hydraulic chamber, the hydraulic actuator being coupled to the hydraulic chamber and being arranged to control a volume of hydraulic fluid in the hydraulic chamber for operating the upper portion between the retracted position and the extended position.
 4. The tool according to claim 1 wherein the lower portion of the hydraulic lifting assembly is arranged to be supported on the drive head.
 5. The tool according to claim 1 wherein said at least one bearing member includes a bearing assembly supporting the upper hollow shaft member rotatably on the upper portion of the hydraulic lifting assembly and wherein the lower portion of the hydraulic lifting assembly is arranged to be supported on the drive head in fixed relation to the tubing string.
 6. The tool according to claim 1 wherein said at least one bearing member includes a bearing assembly supported between the lower portion of the hydraulic lifting assembly and the lower hollow shaft member such that the lower hollow shaft member is rotatably and radially supported relative to the lower portion of the hydraulic lifting assembly.
 7. The tool according to claim 1 further comprising a spline connection slidably coupling the upper hollow shaft member to the lower hollow shaft member.
 8. A rod driving tool for longitudinally positioning and driving rotation of a rod string relative to a tubing string receiving the rod string therein, the tool comprising: a drive head including housing supported above the tubing string and a rotatable output arranged to receive the rod string concentrically therethrough; a rod clamp arranged to be clamped about the rod string at a location spaced above the drive head; an upper hollow shaft member arranged to be fixed to the rod clamp so as to be arranged to receive the rod string therethrough and be arranged rotate with the rod string; a lower hollow shaft member slidably coupled to the upper hollow shaft member such that the upper and lower hollow shaft members are rotatable together with one another and are longitudinally adjustable relative to one another; the lower hollow shaft member being coupled to the rotatable output of the drive head for rotation therewith relative to the housing of the drive head; a hydraulic lifting assembly comprising: a lower portion supported on the housing of the drive head; an upper portion supporting the upper hollow shaft member and rod clamp thereon; the upper portion being coupled to the lower portion so as to be longitudinally movable relative to the lower portion between a retracted position in which the rod clamp is supported thereon at a first elevation relative to the tubing string and an extended position in which the upper portion is raised upwardly relative to the retracted position and the rod clamp is supported thereon at a second elevation relative to the tubing string which is greater than the first elevation; and a hydraulic actuator arranged to operate the upper portion between the retracted position and the extended position; and at least one bearing member supporting the upper hollow shaft member for rotation relative to the housing of the drive head.
 9. The tool according to claim 8 wherein the upper and lower portions of the hydraulic lifting assembly comprise tubular casings which are telescopically connected.
 10. The tool according to claim 8 wherein one of the upper portion and the lower portion comprises a hydraulic chamber and the other one of the upper portion and the lower portion comprises a piston received within the hydraulic chamber, the hydraulic actuator being coupled to the hydraulic chamber and being arranged to control a volume of hydraulic fluid in the hydraulic chamber for operating the upper portion between the retracted position and the extended position.
 11. The tool according to claim 8 further comprising a spline connection slidably coupling the upper hollow shaft member to the lower hollow shaft member. 